The present invention relates to an apparatus for the perfect binding of print products, for example, to form print articles such as book blocks, books, or brochures. The apparatus comprises successively arranged and jointly driven clamping devices that are adapted to hold loose and/or unbound print products gathered into loose book blocks. The apparatus also comprises one or more processing stations that are arranged along a circulating path between a feeding station for the gathered print products, and a delivery station for the bound print articles. The clamped-in book blocks face the processing stations with an overhang, which projects freely from the clamping device and forms the spine of a print product.
Apparatuses of this type are often referred to as “perfect binders.” They are generally accompanied by an upstream gathering device in which folded print products are stacked one above the other, and are gathered to form a loose book block, that is subsequently supplied to the perfect binder while positioned upright on its spine. The print products can be gathered and/or collected while positioned in the conveying direction (as disclosed in Swiss Patent No. CH 504 977) or while transverse to the conveying direction (as disclosed in European Patent Application No. EP 0 712 736).
The individual, unbound book blocks are transferred using a conveying section, for example, along a slanted path, and are inserted from below into tongs. The tongs are arranged successively, and are driven jointly along a circulating path. The tongs hold the unbound book blocks such that they face the processing stations of the perfect binder along the circulating path with an overhang of approximately 10 millimeters for the processing operation.
A relatively heavy construction of the perfect binding apparatus is usually required, due to the high forces exerted while processing the spine, so as to ensure precise and reliable processing.
The circulating path for the clamping devices can be oval or circular. The clamping devices can comprise tongs that grip an initially unbound book block across the length of its back (e.g., along the projecting overhang). The tongs can comprise two gripping elements, of which at least one can move so as to cooperate with the other. Exemplary embodiments of suitable clamping devices are disclosed in Swiss Patent No. CH 504 977 and Swiss Patent No. CH 667 238.
The production rate of a perfect binder is largely based on the machine timing and/or the laws of physics. For that reason, book block clamping devices used in a perfect binder are usually arranged transverse to the conveying direction, allowing them to be spaced at shorter distances to each other than when arranged longitudinally, even though the apparatus expenditure for processing is considerably higher.